The quality of images from cameras and in particular monitoring and surveillance cameras has increased and the requirement of even higher quality images also increases. These requirements have, among other things, resulted in that image sensors having increased number of pixels and decreased pixel pitch are implemented in the cameras. However, in order to achieve higher quality images other features than the number of pixels and the pixel pitch should be considered.
For example, increased number of pixels and the decreased pixel pitch in image sensors makes the image capturing devices increasingly sensitive to misalignments between the image sensor and the optics providing the image sensor with light representing the scene. Hence, the quality from increased number of pixels may be deteriorated if the image sensor is not mounted with high precision.
Today various different methods are used to measure the tilt of the image sensor in relation to the optical axis of the camera, i.e. the optical axis of a lens mounted to the camera.
One method includes use of “golden optics”, i.e. substantially flawless optics. An image of a particular target is captured using the “golden optics” and then may the tilt of the sensor be determined by analysing the captured image. In another method the tilt is measured using a microscope utilising an extremely short depth of field in the microscope. In yet another method a laser beam is directed onto the image sensor along the optical axis of the camera and the reflection is checked for the deflection from the optical axis. One problem of this method is to identify the reflection from the image sensor as a plurality of reflections are created when shining a laser along the optical axis towards the image sensor and it is difficult to determine which one of the reflections that is originating from the image sensor.